Disclosed are intermediate transfer members, and more specifically, intermediate transfer members useful in transferring a developed image in an electrostatographic, for example xerographic, including digital, image on image, and the like, printers, machines or apparatuses. In embodiments, there are selected intermediate transfer members comprised of a conductive component with a core and a conductive shell, and more specifically, an inert core like silica, mica, and the like, and a conductive shell of a n-type semiconductor of, for example, antimony doped tin oxide or oxides. Yet more specifically, the intermediate transfer member, such as intermediate transfer belts (ITB), which is comprised of conductive particles of core shell structure, provides a number of advantages, including excellent dispersibility characteristics, and the capability to achieve a wide range of surface electrical resistivities. An example of the core shell material selected for the intermediate transfer member and intermediate transfer belt (ITB) is ZELEC® ECP 2610-S, which has a unique hollow silica core and conductive antimony doped tin oxide shell. The core shell particle usually possesses a low density due to its hollow core, and an elliptical shape to thereby provide excellent dispersibility in a polymeric solution.
In a typical electrostatographic reproducing apparatus, a light image of an original to be copied is recorded in the form of an electrostatic latent image upon a photosensitive member, and the latent image is subsequently rendered visible by the application of electroscopic thermoplastic resin particles and colorant, which are commonly referred to as toner. Generally, the electrostatic latent image is developed by bringing a developer mixture into contact therewith. The developer mixture can comprise a dry developer mixture, which usually comprises carrier granules having toner particles adhering triboelectrically thereto, or a liquid developer material, which may include a liquid carrier having toner particles, dispersed therein. The developer material is advanced into contact with the electrostatic latent image, and the toner particles are deposited thereon in image configuration. Subsequently, the developed image is transferred to a copy sheet. It is advantageous to transfer the developed image to a coated intermediate transfer web, belt or component, and subsequently transfer with a high transfer efficiency the developed image from the intermediate transfer member to a permanent substrate. The toner image is subsequently usually fixed or fused upon a support, which may be the photosensitive member itself, or other support sheet such as plain paper.
In electrostatographic printing machines wherein the toner image is electrostatically transferred by a potential difference between the imaging member and the intermediate transfer member, the transfer of the toner particles to the intermediate transfer member and the retention thereof should be substantially complete so that the image ultimately transferred to the image receiving substrate will have a high resolution. Substantially 100 percent toner transfer occurs when most or all of the toner particles comprising the image are transferred, and little residual toner remains on the surface from which the image was transferred.
Intermediate transfer member advantages include enabling high throughput at modest process speeds, improving registration of the final color toner image in color systems using synchronous development of one or more component colors using one or more transfer stations, and increasing the range of final substrates that can be used. However, a disadvantage of using an intermediate transfer member is that a plurality of transfer steps is usually needed allowing for the possibility of charge exchange occurring between toner particles and the transfer member which ultimately can lead to less than complete toner transfer. This results in low resolution images on the image receiving substrate and also image deterioration. When the image is in color, the image can additionally suffer from color shifting and color deterioration with a number of transfer stops.
In embodiments, the resistivity of the intermediate transfer member is within a range to allow for sufficient transfer. It is also desired that the intermediate transfer member have a controlled resistivity, wherein the resistivity is virtually unaffected by changes in humidity, temperature, bias field, and operating time. In addition, a controlled resistivity is of value so that a bias field can be established for electrostatic transfer. Also, it is of value that the intermediate transfer member not be too conductive as air breakdown can possibly occur.
In U.S. Pat. No. 6,397,034, there is disclosed the use of a fluorinated carbon filler in a polyimide intermediate transfer member layer. However, there are disadvantages associated with these members such as undissolved particles frequently bloom or migrate to the surface of the polymer layer which leads to nonuniform resistivity characteristics, which in turn causes poor antistatic properties and poor mechanical strength. Also, the ionic additives present on the surface of the belt may interfere with toner release, and bubbles may appear in the conductive polymer layer, some of which can only be seen with the aid of a microscope, others of which are large enough to be observed with the naked eye, resulting in poor or nonuniform electrical properties and poor mechanical properties.
In addition, the ionic additives themselves are sensitive to changes in temperature, humidity, and operating time. These sensitivities often limit the resistivity range. For example, the resistivity usually decreases by up to two orders of magnitude or more as the humidity increases from about 20 percent to 80 percent relative humidity. This effect limits the operational or process latitude of the intermediate transfer member.
Therefore, it is desired to provide a weldable intermediate transfer belt, which has excellent transfer ability. It is also desired to provide a weldable intermediate transfer belt that may not have puzzle cut seams, but instead has a weldable seam, thereby providing a belt that can be manufactured without such labor intensive steps as manually piecing together the puzzle cut seam with ones fingers, and without the lengthy high temperature and high humidity conditioning steps. It is also desired to provide an acceptable circumference weldable belt for color machines.